1-s2.0-0889540689901613-main
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A cephlalometric study of 32 North American black patients with anterior open bite Osmond G. Jones* Washington, D.C. The piirpose of this research project was,to investigate a group of 32 North American black patients witti anterior opeti bite a,nd compare them to th& Noti, American black norms established by Altemus’ and Drummond2 and to white populatiqn norms Mablished by Steiner.3 In addition, values weke establitihed for blaCk patients bq use of ,the overbite depth indicator of Kim.” The method involved the tracing of Ia~eral e&ptialdmetric radiugraphs of 32 patients with anterior open bite using the analyses of Ttieed,‘*,Steiner,3 and Kim.“ The resulting angles were added and the means and standard deviations calculated. 0r1 the basis. of the criteria us&d for this study, the significant findings were as follows: (1) the maxilla was normally positioned to the cranial base; (2) the upper and lower incisors w&e procumberit with an acute interi,ncisal reltitionship; (3) the mandibular position tended to be retrllsive to the cranial base; (4) the lower facial height was greater and the mandibular plane angle (GoGn-SN) was smaller than white population standards; and (5) the overbite depth indicator of Kim4 was smaller for this gro’up than for the white population studied. (AM J ORTHOD DENTOFAC ORTHOP 1$89;95:289-96.) T he patient with an anteridr open bite has one of the most difficult orthodontic problems to cor- rect. The cause of the anterior open bite may be both complex and difficult to establish tind yet is critical iri developing a treatment iegimen -that will produce St&- bility and satisfactory cosmetic results. Although nor- mal faces are different for the vtious racial groups, cephalonietric stand&rds are available for both blacks and whites.‘.f However, our knowledge largely repre- sents the white population. The treatment of patients .with anterior open bite raises as many problems as determining the ‘calfse. HellmanS (in 1931) and Nahouri-~~-~ (in 1974) found as many successes; as there were failures in the treatment of open bite cases. In 1969, Richardson”,” stated that the prognosis for these cases was -either good or poor. In 197 1, Kim4 reported that the state of cephalometric analysis and knowledge of the subject was inadequate to diagnose an open bit& or deep bite tendency. The purpose of this study was to evaluate the ceph- alometric feitures of a gro’up of North American black patients with anterior oijen bite. These data were COT- pared to standards established for both white and black racial groups with the hope that these findings would be useful in differential diagnosis and treatment plan- ning for orthodontic patients. *Assistant Professor, Howard University College of Dentistry, Department of Orthodontics. METHOD This research involved the use of lateral cephalo- metric radiographs of 32 black patients, aged 8 to 39 years, with clinically diagnosed anterior open bite. The group was divided into 25 female and seven male sub- jects. Tracings were made of x-ray films and landmarks were identified by use of the analyses of Steiner,3 Tweed,” and Kima (Figs. 1 through 3). The occlusal planes (Fig. i) and the A-B plane (Fig. 3) were drawn. Total facial height and lower facial height were mea- sured according to Richardson”,” and Nahoum6‘9 (Fig. 2), ahd the relevant angles for the Steiner’ and Tweed” analyses were recorded. The sample was divided further into skeletal and dental groups by arbitrarily usihg GoGn-SN angle of 32.5” as a division. Anterior skeletal open bites were classified above this division. Tracings were done with a hard pencil on 0.003 matte acetate tracing paper and measurements were ob- tained using cephalometric tracing equipment. * The data were presented in tabular form and the mean, range, and standard deviation were calculated. RESULTS Tables I through V include data collected without dividing the sample into skeletal and dental anterior open biteS; Tables VI and VII divide the sample into skeletal and dental anterior open bites. A comparison (Table I) between the present *Unitek Corporation. Monrovia, Calif. 289
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Acephlalometricstudyof32NorthAmericanblack patientswithanterioropenbite OsmondG.Jones* Washington,D.C. Thepiirposeofthis researchprojectwas,toinvestigateagroupof32NorthAmericanblackpatients wittianterioropetibitea,nd comparethemtoth& Noti,Americanblacknormsestablishedby AltemusandDrummond2andtowhitepopulatiqnnormsMablishedbySteiner.3 In addition,values weke establitihedforblaCk patientsbquseof ,theoverbitedepthindicatorofKim. Themethod involvedthetracingofIa~eral e&ptialdmetricradiugraphsof32patientswithanterioropenbiteusing theanalysesofTtieed,*,Steiner,3andKim. Theresultingangleswereaddedandthemeansand standarddeviationscalculated.0r1 thebasis. of thecriteriaus&d forthisstudy,thesignificantfindings wereas follows:(1) themaxillawasnormallypositionedtothecranialbase;(2) theupperandlower incisors w&eprocumberitwithanacuteinteri,ncisal reltitionship;(3) themandibularpositiontended toberetrllsivetothecranialbase;(4) thelowerfacialheightwasgreaterandthemandibularplane angle(GoGn-SN)wassmallerthanwhitepopulationstandards;and(5) theoverbitedepthindicator ofKim4 wassmallerforthisgroup thanforthewhitepopulationstudied.(AMJORTHODDENTOFAC ORTHOP1$89;95:289-96.) T hepatientwithananteridropenbitehas oneofthemostdifficultorthodonticproblemstocor- rect.Thecause oftheanterioropenbitemaybeboth complexanddifficulttoestablishtindyetis criticaliri developingatreatmentiegimen-thatwillproduceSt&- bilityandsatisfactorycosmeticresults.Althoughnor- malfacesaredifferentforthevtiousracialgroups, cephalonietricstand&rdsareavailableforbothblacks andwhites..fHowever,ourknowledgelargelyrepre- sents thewhitepopulation. Thetreatmentofpatients.withanterioropenbite raisesasmanyproblemsasdeterminingthecalfse. HellmanS(in1931)andNahouri-~~-~(in1974)foundas manysuccesses;as therewerefailuresinthetreatment ofopenbitecases. In1969,Richardson,statedthat theprognosisforthesecases was -either goodorpoor. In197 1,Kim4reportedthatthestate ofcephalometric analysisandknowledgeofthesubjectwasinadequate todiagnoseanopenbit& ordeepbitetendency. Thepurposeofthisstudywasto evaluatetheceph- alometricfeituresofa group ofNorthAmericanblack patientswithanterioroijenbite.These datawereCOT- paredtostandardsestablishedforbothwhiteandblack racialgroupswiththehopethatthesefindingswould beusefulindifferentialdiagnosisandtreatmentplan- ningfororthodonticpatients. *AssistantProfessor,HowardUniversityCollegeofDentistry,Departmentof Orthodontics. METHOD Thisresearchinvolvedtheuseoflateralcephalo- metricradiographsof32blackpatients,aged8to39 years,withclinicallydiagnosedanterioropenbite.The groupwas dividedinto25femaleandseven malesub- jects.Tracingswere madeofx-rayfilmsand landmarks wereidentifiedbyuseoftheanalysesofSteiner,3 Tweed,andKima(Figs.1 through3).Theocclusal planes (Fig.i)andthe A-Bplane(Fig.3) weredrawn. Totalfacialheightandlowerfacialheightweremea- sured accordingtoRichardson,and Nahoum69 (Fig. 2),ahdthe relevantangles fortheSteinerandTweed analyses wererecorded.Thesample was dividedfurther intoskeletalanddentalgroupsbyarbitrarilyusihg GoGn-SNangleof32.5as a division.Anteriorskeletal openbiteswereclassifiedabovethisdivision. Tracingsweredonewithahardpencilon0.003 matteacetate tracingpaperand measurementswere ob- tainedusingcephalometrictracingequipment.*The datawerepresentedintabularformandthemean, range,andstandarddeviationwerecalculated. RESULTS TablesIthroughVincludedatacollectedwithout dividingthesampleintoskeletalanddentalanterior openbiteS;TablesVIandVIIdividethesampleinto skeletalanddentalanterioropenbites. Acomparison(TableI)betweenthepresent *UnitekCorporation.Monrovia,Calif. 289 290Jones Am.J.Orthod.Dentofac.Orthop. April1989 KEY S-nidpointoiPituitaryFoisa NaNaiion SN=Cranialbaseplane 60.Gonion Gn=Gnathion A=Pointofgreatestconvexityon theanteriorofthrmaxilla B=Pointofgreatestconvexityon theanteriorofthemandible Fig.1.Steinersanalysis. studyandnormsestablishedbyAltemu?showedthe following: i .TheopenbitepatientsdidnotdemonstrateSNA anglesthatweiesignificantlydifferentfrom blacknorms. 2.TheSNBvalueS usuallyw&eless thantheblack norms. 3.SNDanglewasgreaterinopenbitecases, but was considerablyless in thoseidentifiedaiskel- etalopenbites. 4.Theupperandlowerincisorsweremorepro- cumbentwithopen bitecases and the interincisal anglewassignificantlysmillerthanthenorm. 5.Openbitepatientshadlarg&GoGn-SNangles. Standarddeviationsforthenormsestablished. by AltemuswereriotavailableandpreventedstatiStica comparisonwiththefiguresfromtheopenbitevalues. IncomparingthesefindingstotheTweed*norms establishedby&ummond*(TableII),theFMAand IMPAangles werenot foundto be significantlydifferent fromthenorm.TheopenbiteFMAanglewaslarger andIMPAanglewassmallerthantheblacknorms. Whenthe blackopen bitecases were comparedwith thewhiteopenbitecases (TableIII),itwasseen that bothracialgroupshad$NAvaluessimilartotheirre- spectivenotis.However,SNBs and interincisalangles weresmallerandGoGn-SNvalueswerelargerthan normal.ThewhitedatahadlargerGoGn-SNvalues. TableIVshows thatthemean openbiteFMAangle wassmallerfortheblacksubjectsthanthatforwhite subjects. Bothopenbiteracialgroupshadincreasedlower facialheight,butoverallblacksubjects hadthelarger value.Theoverbitedepthindicator(ODI)waslower forblacksubjectsthanforwhitesubjects(TableV). Thesamplewasdividedintotwogroupsfo;the iteine?analysis (Table VI).GroupI (skeletal open bite) hadGoGn-SNangleabove32.5andgroupII(dental openbite)hada GoGil-SNanglebelowthispoint. Thereweredifferencesbetweenthegroups.The skeletaltypeshowednomaxillaryprotrusion(SNA, 85=norm).Themandible@ND,74.9)displayed downwardand backwardrotationor retrusion.Ttieskel- etalgroupalsohadmaxillaryincisalprocumbency (&NA,25.5),butthiswasless thanthedentalgroup (I-NA,27;3).Thedentaltypes exhibitedmaxillaryand Volume95 Number4 Cephdometricstudyofblackpatientswithanterioropenbite291 KEY ANS=Anteriornasalspine PNS=Posteriornasalspine ANS-PNS=Palatalplane Ii-Nanton N-N=Totalfacialheight N-ANS-Upperf&J81height ANSM=Lowerfacialheight LA=Longaxis6fthelowerIncisor FrankfurtPlrne=Llnairolathe upperborderoftheexternal auditorynertustothelower borderoftheorbit MandibularPi@no=Linetangential ttithelowerborderofthe mandible Fig.2.Tweedsanalysis. TableI.Comparisonofnormalandopenbitedatabyuse ofSteinersanalysis Blacknorm(Altemus)Blackopenbite(presentsrudyj MeanSD(2)MeanSD(2) SNA85.50 - 85.704.79 SNB81.00 - 79.00Q4.78 ANB4.505.723.57 SND77.00 - 78.605.31 LNA23.00 - 26.037.50 A-NA7.00mm - 8.25mm2.97 LT 119.00 - 111.1011.57 T-NB34.0037.907.82 T-NB10.00mm - ll.OOmm3.36 GoGn-SN32.50 - 35.605.72 mandibularprotrusion(SNA,87;SNB,83,respec- tively)andhadagreaterprocumbencythanthenorm forthemaxillaryincisors(A-NA,27.3). Patientswithskeletalopenbiteexhibiteda greater lowerincisorprocumbency(T-NB,38.5)thanthose withdentalopenbite,and hada moreacute interincisal angle(A-T, 110.8)thaneitherskeletal(blackpatients, 1-T,119;whitepatientsA-T,120)ordentalQ-T, 1i2.20)norms. ComparisonofgroupIandgroup11 fortheTweed 292Jones Am.J.Orrhod.Dentofac.Orthop. April1989 KEYd. 1 A-BPlane=LineJoiningpointsA(LB 9 fromSteinersanalysis c!DI=Thesti.oftheangieformedby8 1.TheHondibular&dA&BPlaner 2.TheFr.arikfUrtandPdlat?lPlanesa, Fig.3.Kimsanalysis(overbitedepthindicator[ODI]). TableII. Comparisonofnormalandopenbitedatabyuse ofTweedsanalysis FMA IMPA FMIA Blacknorm(Drummomf)Blackopenbite(presentstudy) MeanSD(2)MeanSD(*) ;0.6&4.7031.566.67 100.005.0099.507.90 49.405.7049.209.70 analysesindicatedthatFh4Aanglewaslargerforpa- tientswithskeletalopenbiteandtheIMPAanglewas largerforpatientswithdentalopenbite(TableVII). (Thisimpliedthatthe skeletalgroupshoweddownward andbackwardrotationofthemandible.)Thedental groupgenerallyhadsignificantlylowerincisalprocum- bency.Upperfacialheightswerelowerforskeletal open bitecases thanforthedentalcases. ForKimsoverbitedepthindicator,4theskeletal grouphadasmallerODIthanthedentalgroup.Both groupswerebelowthewhitenormof74.50. Dl!$ZUSSlON TableIcomparesthenormaldataestablishedby AltemuswiththeopenbitedatafortheSteinetianal- ysisestablishedbythecurrentstudy.Allthenormal values werewithinone standarddeviationofthe means fortheopenbitevaluesinthestudy.Astatisticalcom- parisonwasnotpossiblesincestandarddeviationsfor thenormalmeans werenotavailable.Instead,theclin- icalsignificanceofthedatawascompared. Therelationshipof.-pointA(seeFig.1)onthe maxillatothe cranialbase (asindicatedbyangleSNA) didnotchangesignificantlyfromthenormalmean. SimilarfindingswerereportedbyHapak13 inastudy of52whitepatientsin1964.Therelationshipofthe mandibleto the cranialbase as shownby theSNB angle indicatedthat the mandiblerotateddownwardand back- ward.ThiswascontradictedbytheSNDmeanvalue, whichincreased.Theincreasewasattributedtothe inclusionofbothskeletalanddentalopenbitecases in thegroupsused forthe study.WhenincludingtheSND Volume9s Number4 Cephnlometricstudyofblackpatientswithanterioropenbite293 TableIII.Comparisonofblackandwhiteopenbitedatabyuse ofSteinersanalysis Blackopenbite(presentstudy)Whiteopenbite(Hapak)* MeanSD(?IMeanSD(*i SNA SNB ANB AT GoGn-\SN ___- *Otherdataunavailable. 85.654.7980.IO3.23 79.904.7875.903.79 5.723.574.202.88 111.1011.57120.0010.49 35.605.7238.567.19 TableIV. Comparisonofblackandwhiteopenbitedatabyuse ofTweedsanalysis Blackopenbite(presentstudy)Whiteopenbite(Hapak) MeanSD(2)MeanSD(2) FMA IMPA FMIA 31.566.67 99.507.90 49.209.70 33.40 - Unavailable Unavailable TableV. Comparisonofblackandwhitedata:Overbitedepthindicator(ODI)andupperfacialheight/total facialheight(IJFH/TFH)byuse ofKimsanalysis Blackopenbite(presentstudy)Whitedata MeanSD(2)MeanSD(?) ODI66.146.7814.506.07norm(Kim4) UFHiTFH40.90%3.5842.80%-Openbite(Hapal?)* *NormUFHITFHunavailableforblacksubjects. valuesforthedentalopenbites,themeanvaluefor SNDanglewouldbeelevatedbecausetheskeletalre- lationshipswereclosertothenorm. Thevaluesfortherelationshipoftheupperincisor tothemaxillaryI-NAangleandmillimetermeasure- mentindicatedthattheupperincisorswerenoticeably moreprocumbentinopenbitecases. Thiswas reported in previousstudies such as the onebyHapak13 in1964. Thediminishedinterincisalanglealso indicatedthatthe incisorsweremoreprocumbent.Theanglemadeby thelowerincisorandthemandible(T-NB)showeda markedprocumbencyofthelowerincisors. Themandibularplaneangle(GoGn-SN)showedan increase abovet.he normalmean.Mizrahi,14Hellman, Nahoum,6-and others.indicatedin theirstudies that the mandibularplaneangle increased in open bitecases. TableIIshowsthefindingsofthe presentstudyfor theTweedIanalysis.Theresultswereunexpected. ComparedwiththenormsestablishedbyDrummond (TableII),theanglebetweentheFrankfortplaneand themandibularplane(FMA)increasedsignificantlyat the0.01level.TheIMPAand FMIAanglesshowedno significantdifferencefromthenorms.Thiswassome- whatsurprisingsinceareviewoftheliteraturehad indicatedthatchangesinthelowerincisorangulation shouldhavebeenexpected. Ina comparisonbetweenblackandwhitepatients withanterioropenbite(TablesIIIandIV),significant numericaldifferenceswerenoted.Bothgroupsalso exhibitedthesame trends.For example,bothhadSNA valuesthatwerevirtuallythesame as normalandSNB anglewasreducedinbothgroups.Thedataforwhite patientsweretakenfromresearchbyHapakin1964 onan openbitesampleof52cases. Thearticledidnot specifywhetherthegroupwasskeletalordentalin nature. 294Jones Am.J.Orthod.Dentofac.Orrhop. April1989 TableVI.ComparisonofgroupIskeletalandgroupIIdentaldatabyuse ofSteinersanalysis SNA SNB ANB SND I-NA A-NA 1T T-NB T-NB GoGn-SN Skeletalopenbite,groupIDentalopenbite,groupII (presentstudy)(presentstudyJ MeanSD()MeanSD(2) 85.004.1087.303.50 78.703.9683.003.00 6.303.105.602.29 74.904.7279.303.30 25.507.6027.307.60 7.90mm2.809.20mm3.50 110.8010.37112.2014.90 38.507.7036.109.19 11.80mm3.269.00mm2.69 38.303.7928.703.57 TableVIIA.ComparisonofgroupIskeletalandgroupIIdentaldatabyuse ofTweedsanalysisand KimsODI Tweedsanalysis FMA IMPA FMIA Kimsoverbitedepthindicator(ODI) ODI GroupIopenbite (presentstudy) MeanSD(2) 33.305.50 99.107.20 47.719.10 65.506.60 GroupIIopenbite (presentstudy) MeanSD(2) 27.507.70 100.609.78 53.0010.60 67.807.20 TableVIIB.UFH/TFHdata(meanfSD) UFIWTFH GroupIopenbite (presentstudy) 40.40%*3.90 GroupIIopenbite (presentstudy) 42.20%i 2.20 Steinersdata3 forthetworaces werecomparedin TableIIIand the differencesweresignificantat the 0.05 level.Thedifferencesin theSNA,SNB,and 1: T values weresignificantat the 0.001level.The GoGn-SNangle of38.56t7.19inwhitedentalopenbitesubjects was higherthan thatof blacksubjects-35.6?5.72; it was approximatelythesame as thatforblacksubjects intheskeletalgroup-38.3+3.79.Thiswasan unusualfinding;possiblyHapak13 studiedagroupof predominantlyskeletalopenbitepatients.Thismight explainthesimilaritybetweentheraces intheskeletal cases. OnlyangleFMAwasavailableforracialcompar- isonswiththeTweedanalysis(TableIV)andasta- tisticalcomparisonwasnotpossiblebecause ofincom- pletedata. TableVindicatesthattheblackopenbitepatients hadlonger,lowerfacesthanthewhitepatients.This was an expectedfindingsince studies on normalpatients byAltemusalreadyhas displayedthistrend. Theblackpatientsampleevaluatedinthisstudy showedthefollowing: 1.Upperfacialheighttototalfacialheight- 40.9-+3.58 2.Kimsoverbitedepthindicator(OD1)4- 66.14f6.78;thenormestablishedbyKim Volume95 Number4 Cephalometricstudyof blackpatientswithanterioropenbite295 on119whitepatientswas74.5+6.07.The differencebetweenthesetwofigureswassig- nificantatthe0.001level. Throughouttheliteratureithadbeenstatedthat openbitepatientshadsignificantlylargerGoGn-SN anglesthanthenorm(32.5)establishedbyAlte- mus(HellmaqsNahoum,6-9andMizrahi14).Na- houm6-9 statedthatthereweretwotypesofopenbite cases-namely,skeletal(groupI)anddental(group II).Themeanmandibularplaneangle(GoGn-SN)pro- ducedbythisstudy,althoughlargerthanthe norm,was notas largeas, mighthavebeenexpected.Itwasbe- lievedthatthecases includedbothskeletalanddental types.Aneffortwasmadetoidentifythetwogroups bydividingthe cases intoonegroup(groupI,skeletal), whichhadGoGn-SNangleshigherthanthenorm (32.5,Altemus),and anothergroup(groupII,dental) withGoGn-SNangles 32.5and below.The mandibular planeangle(GoGn-SN,32.5)wastakenfromthe normsestablishedforblacksbyAltemus(TableI). InTableVIthetwogroupswerecomparedand Studentsttestappliedtocheckthenumericaldiffer- encesforstatisticalsignificance.Thedifferencebe- tweentheSNAvaluesforbothgroups(skeletaland dental)wasnotsignificantatthe0.1level,norwas theremuchdifferencebetweentheoverallfigurefor openbitesfor1:his studyandthenormestablishedby Altemus.Thereforeit seemedthattheSNAanglewas notsignificantlychangedbytheopenbitecondition. ThiswasalsoafindingofHapakinhisstudyof52 openbitewhitepatients. TheSNBvaluesforthetwogroups(skeletaland dental)weresignificantlydifferentatthe0.01level. The skeletal openbite groupI had a reducedSNBangle. Thedentalopen1bitegroupIIdisplayedlittledifference fromthenorm.whiletheskeletalgrouphada signifi- cantlyreducedSNBangle.TheANBdifferencebe- tweenthetwogroupswasnotstatisticallysignificant atthe0.1level.Itcanbe concludedthatskeletalopen bitecases hadsignificantlyreducedSNBandSNDan- gles.Thiswascaused bybackwardanddownwardro- tationofthemandible. Thepositionoftheupperincisorsin relationtothe NAlinewasmoreprocumbent;thedifferencebetween thetwogroupswas statisticallysignificantand theden- talopenbitegroupshowedgreaterprocumbency.This wasnotunexpectedsinceincreasedprocumbencyof theincisorswas necessary to producean openinginan otherwiseskeletallynormalfaceanddentition. Theinterincisalangleshowednostatisticallysig- nificantdifferenfzebetweenthetwogroups;theangle wasmoreacutethanthenorminbothgroups.Itwas expectedthattheinterincisalanglewouldhavebeen even moreacute in dentalopenbite cases. Skeletal open bitescausedbywhatSchudyhas describedas a hy- perdivergentskeletalpatternwouldneedlessdental procumbencytoproduceanopenbite. Thelowerincisorposition(T-NB)forbothgroups showednostatisticaldifferencebetweenthegroups. Bothhadgreaterprocumbencythanthenorm. ThedatafortheTweedanalysisforbothgroups werecomparedinTableVII.Ofthethreeparameters, onlyone-theFMAangle-showedasignificantdif- ferencebetweenthegroupsatthe0.1level.Thiswas expectedsincethebasisonwhichthetwogroups weredifferentiatedwasaGoGn-SNangleabove normalandGoGn-SNbelownormal,normaltakento be32.5. Theratioofupperfacialheightto totalfacialheight showednosignificantdifferencebetweenthe groupsat the0.1level.Thiswas a particularlysurprisingfinding becauseoneofthepointsemphasizedintheliterature byMizrahi14wasthatskeletalopenbitepatientshad greaterfacialheights.Thereasonthetwogroups showedlittledifferencemayhave been the samplesize. Morestudies need tobe undertakenonopenbitecases. Itispossiblethattheextremeswithinthetwogroups caused thevalues toaverageout.Thevalues produced bythetwogroupsfromKimsODPwerenotstatisti- callydifferentatthe0.1level. CONCLUSIONS Thefollowingconclusionsweredrawnfromthis study. 1.Blackanterioropen bite patientshad SNAangles close tothe norm;SNBangles wereless thanthenorm. Interincisalanglesweremoreacutethannormaland bothupperandlowerincisorsweremoreprocumbent thanthenorm. 2.Dentalanterioropenbitecases (groupII)had maxillaryprotrusionandagreaterupperincisalpro- cumbency.However,skeletalopenbitepatients(group I)showedbackwardanddownwardrotationofthe mandible,greaterlowerincisalprocumbency,and GoGn-SNvaluesabovethenorm. 3.A comparisonof anterioropenbite data forblack andwhitesubjects showedthatblacksubjects hadlon- gerlowerfacialheightsandwhitesubjectshadnu- mericallylargerGoGn-SNvalues. REFERENCES 1.AltemusLA.Acomparisonofcephalometricrelationships.An- gleOrthod1960;30:223-40. 2.DrummondRA.Adeterminationofcephalometricnormsforthe Negrorace.AMJORTHOD1968;54:670-82. 3.SteinerCC.Cephalometricsinclinicalpractice.AngleOrthod 1959;29:8-28. 296Jones Am.J.Orrhod.Dentojac.Orthop. April1989 4.KimYH.Overbitedepthindicatorwithparticularreferenceto anterioropen-bite.AMJORTHOD1974;65:586-611. 5.HellmanM.Open-bite.INTJORTHOD1931;17:421. 6.NahoumH.Verticalproportionsandthepalatalplaneinanterior open-bite.AMJORTHOD1971;59:273-82. 7.NahoumH.Varietiesofanterioropen-bite.AMJORTHOD 1972;61:486-92. 8.NahoumH.Anterioropen-bite:acephalometricanalysisand suggestedtreatmentprocedures.AMJORTHOD1975;67:513-21. 9.NahoumH.Verticalproportions:aguideforprognosisandtreat- mentinanterioropen-bite.AMJORTHOD1975;72:128-46. 10.RichardsonA.Skeletalfactorsinanterioropen-biteanddeep overbite.AMJORTHOD1969;56:114-27. 11.RichardsonA.Dento-alveolarfactorsinanterioropenbiteand deepoverbite.DentPratt1970;21:53-7. 12.TweedCH.TheFrankfort-mandibularplaneangleinorthodontic diagnosis,classification,treatmentplanning,andprognosis.AM JORTHODORALSURG1946;32:175-230. 13.HapakFM.Cephalometricappraisaloftheopenbitecase.Angle Orthod1964;34:65-73. 14.MizrahiE.Areviewofanterioropenbite.BrJOrthod1978;s: 21-7. 15.SchudyFF.Thecontrolofverticaloverbiteinclincialortho- dontics.AngleOrthod1968;38:19-39. 16.AthertonJD.Theinfluenceofthefaceheightupontheincisor occlusionandlipposture.DentPratt1965;15:227-31. 17.BaumeL.Uniformmethodsfortheepidemiologicassessment ofmalocclusion.AMJORTHOD1974;66:251-72. 18.BjorkA.Thefaceinprofile.Lund,Sweden:BerlingskaBok- tryckeriet,1947. 19.DeCosterL.Open-bite.INTJORTHOD1936;22:912-38. 20.GershaterMM.Theproperperspectiveofopenbite.AngleOr- thod1972;42:263-72. 21.HelmS.MalocclusioninDanishchildrenwithadolescentden- tition:anepidemiologicstudy.AMJORTHOD1968;54:352-66. 22.JohnsonEL.TheFrankfort-mandibularplaneangleandthefacial pattern.AMJORTHOD1950;36:516-33. 23.KandilE,FahmyMS.Openbiteandthumbsucking.JMed Liban1974;27:219-22. 24.LemerHI.Thumbsuckinganddentalocclusion.AMJORTHOD 1955;41:640. 25.MillsLF.Theprevalenceofmalocclusioninapopulationof 1,455schoolchildren.JDentRes1966;45:332-6. 26.MossML.Differencesbetweenthefunctionalmatricesinan- terioropen-biteandindeepbite.AMJORTHOD1971;60:264- 80. 27.PrakashP,MargolisH.Dento-craniofacialrelationsinvarying degreesofoverbite.AMJORTHOD1952;38:657-73. 28.RickettsRM.Theinterdependenceofthenasalandoralcapsules. In:McNamaraJAJr,ed.Naso-respiratoryfunctionandcranio- facialgrowth.CraniofacialGrowthSeries.AnnArbor:1979. CenterforHumanGrowthandDevelopment,Universityof Michigan. 29.SassouniV,NandaS.Analysisofdentofacialverticalpropor- tions.AMJORTHOD1964;50:801-23. 30.SubtelnyJ,SakudaM.Open-bite:diagnosisandtreatment.AM JORTHOD1964;50:337-58. 31.SwinehartEW.Relationofthumb-suckingtomalocclusion.AM JORTHODORALSLRG1938;24:509. 32.WylieW,JohnsonE.Rapidevaluationoffacialdysplasiainthe verticalplane.AngleOrthod1952;22:165-82. 33.SassouniV.Aclassificationofskeletalfacialtypes.AMJORTHOD 1969;55:109-23. 34.SwindlerD,SassouniV.Openbiteandthumbsuckinginrhesus monkeys.AngleOrthod1962;32:27. 35.KincaidRM.Frequencyofdeglutitioninitsrelationshipto overbite.AngleOrthod1951;21:34. 36.LearCS.Variabilityofheadpostureduringsleepandconsid- erationsrelatingtopalateanddentalarchform.ArchOralBiol 1967;12:1229-40, 37.KazmierczakD.Roleofabnormalitiesofdeglutitionintheetiol- ogyofinfraclusion.RevStomat1966;67:29-35. 38.RuttleA,QuigleyW,CrouchJ,DwanG.Aserialstudyofthe effectsoffingersucking.JDentRes1953;32:739-48. Reprintrequeststo: Dr.OsmondG.Jones DepartmentofOrthodontics CollegeofDentistry HowardUniversity 600WStreet,NW Washington,DC20059
